TRS-80 DOS - RapidDOS (RAPIDOS, Rapidynamic Software)

RAPIDOS was a small, memory-resident operating system whose one trick was to read or write an entire disk track in a single revolution of the drive. Rapidynamic Software first sold it as the engine of a fast disk formatting and duplicating program. Its slogan was "26-second backup": a full 40-track double density diskette copied and verified in 26 seconds, and formatted, copied and verified in 42.

RAPIDOS had a second life as the run-time DOS for Rapidynamic's high-resolution games, sold by Micro-Labs, above all Tournament Chess. That is how most owners met it. It is also why it came up again in 1989, when the games would not run on Model 4s fitted with the MISOSYS XLR8er or the Alpha Technology speed-up board.

1984: The Rapid Disk Duplication Program

Rapidynamic's first advertisement, "26-SECOND BACKUP! TRS-80 Model I/III/4," ran in the May 1984 80 Micro. "The secret of the speed is RAPIDOS," it said. RAPIDOS was "a new disk operating system" that could read or write a whole track in one revolution, with versions file-compatible with Model I TRSDOS 2.3, Model III TRSDOS 1.3 and Model 4 TRSDOS 6.0. The program accepted changes to the number of tracks, stepping rate, diskette name, password and date. If there were errors, it tried to recover and displayed full error messages. The manual covered operation, error messages, their causes, and the operating system itself. The program diskette and manual cost $30 and needed a 48K disk system. The same issue's new products column announced the $30 program as "Quick Copies."

The advertisement's sample times, in seconds, assuming no errors:

From September 1984 the advertisement changed its pitch. A double density diskette spins at 300 RPM and holds 4,608 bytes per track, which is 23,040 bytes per second, so why does backing up take so long? "The problem is slow software. The solution is ... RAPIDOS." That version also stressed mass duplication: after one backup, the next one starts with a single keystroke. By then the Model I version backed up TRSDOS 2.3 disks, the Model III version TRSDOS 1.3 disks, and the Model 4/4P version TRSDOS 6.x disks. The advertisements ran through at least November 1984. A February 1985 South Bay TRS-80 Users Group price list carried "Rapidos," a copy utility from Rapidynamic, at $40.

1985: The 80 Micro Review

Gary A. Ludwick reviewed it as "Rapidos: No Waiting" in the July 1985 80 Micro and gave it five stars in every category. He had moved from a Model III to a Model 4P and could not believe how slowly TRSDOS 6.2 formatted and backed up disks. His timings (minutes:seconds):

His one complaint was drive speed. RAPIDOS had trouble reading a disk in one drive that had been backed up in another, and by his account it was far more sensitive than the manual's warning that a speed difference above two RPM would cause problems. The review listed Rapidynamic Software, Inc., 14358 Dyer St., Sylmar, at $30. 80 Micro's 1985 review index lists it among the year's utilities.

1985 to 1989: The Hi-Res Games

Rapidynamic also wrote games and graphics programs for the Radio Shack and Micro-Labs high-resolution boards: Tournament Chess, Tournament Reversi, Match Play Backgammon, 3D Tic-Tac-Toe and Surface Plot II. They were marketed by Micro-Labs, Inc. of Dallas, and every one came on a disk with its own RAPIDOS. A December 1985 NATGUG News review of Tournament Chess ($49) said it came on "a free operating system called RAPIDOS (TRSDOS 6 compatible), which boots while you blink!" Micro-Labs also supplied much of its own hi-res software on RAPIDOS disks (Computer News 80, April 1989).

The duplication program was still around in 1989. In TRSTimes (Volume 2, Number 1, early 1989), a writer who had to make dozens of copies of his Amway programs at a time reported that TRSDOS 1.3's BACKUP took 3 minutes 28 seconds for a disk with 30 of 40 tracks in use. RAPIDOS did the same job, including formatting, in 38 seconds. He was not sure Rapidynamic was still selling it, but said it was available from Recreational Mathematical Software for $30.

The End of Rapidynamic

By early 1989 Rapidynamic could not be found. A reader whose RAPIDOS would not boot with an Alpha Technology 6 MHz speed-up board wrote to both TRSTimes and Computer News 80 asking for the BOOT/SYS source code. He had tried to order the operating system from its author but could not locate them. Ted Carter at Micro-Labs had no solution, and Tim Sewell of The File Cabinet had told him that "Rapid Dynamic Software (authors of RAPIDOS) have apparently gone out of business." Micro-Labs kept selling the games on RAPIDOS disks and patched them for the XLR8er itself (see below).

80 Micro's August 1987 list of "TRS-80 DOSes we have known" included Rapidos.

Rapidynamic sold a separate RAPIDOS for each model. The magazines name these versions:

A RAPIDOS 1.5 also survives. The Model 4 versions use the TRSDOS 6 / LS-DOS directory structure, so standard tools can read their files (Computer News 80, July 1992; The MISOSYS Quarterly, Spring/Summer 1989).

Ludwick explained the speed in 1985: RAPIDOS reads and writes a disk track in a single revolution of the drive. To do that it formats disks somewhat differently from TRSDOS, though not so differently that it affects use. It verifies every read and write and retries when something is wrong. He reformatted several flaky disks with RAPIDOS that TRSDOS 6.2 had locked out sectors on.

The price of single-revolution track I/O was sensitivity to drive speed. The manual said that as long as a drive did not go above 302 RPM all would be well, and that any deviation above 7.5 percent (two revolutions per minute) between drives was likely to cause problems. A Display Speed function runs the selected drive and shows its rotational speed until BREAK is pressed, so the speed can be adjusted with a screwdriver. In 1990 a MISOSYS Quarterly reader complained that RAPIDOS's FORMAT "doesn't know LOCKOUT." He had a terrible time finding disks that met RAPIDOS's expectations, and said the DOS reminded him of "the FIRST CP/M operating systems."

Roy Soltoff of MISOSYS took RAPIDOS apart in 1989 to find out why Tournament Chess hung on an XLR8er. He found a standard directory structure, a BOOT/SYS file, ten utilities (BACKUP, BUILD, COPY, DIRL, FORMAT, FREE, HELP, LIST, PURGE and RENAME) and the CHESS files. "To call Rapidos a 'DOS' is really stretching the imagination," he wrote. What he saw might have been only a run-time version for the games. It provided only nine character device service functions and six disk I/O functions, and the whole run-time facility was stored within the first track of the disk. That is why it booted so fast: on a cold machine it was at its Ready prompt before the screen had warmed up enough to show characters. LS-DOS, by contrast, keeps only its device drivers and a few pages of data (4.5K) in the first track, and has to load another 4.5K of SYS0/SYS and 1.5K of SYS1/SYS before Ready.

Soltoff also described the boot. The ROM boot loader reads track 0, sector 1 into 4300H and executes it. That little boot program reads the BOOT/SYS file starting from sector 2, and BOOT/SYS is a load-image file once you are past the boot sector. The games came in two parts: a small /CMD file (CHESSH, 1.5K) that called into the "DOS" in low memory, and a core-image file (CHESSH/EXE, 31.5K) that it loaded at 2100H. The /EXE files are plain binary images, not partitioned data set files (The MISOSYS Quarterly, Spring/Summer 1989 and Spring 1990).

From Ludwick's 1985 review and the 1989 TRSTimes article:

Gary W. Shanafelt surveyed the hi-res software for Computer News 80 in July 1992 and gave the Rapidynamic programs a category of their own. They were written in machine language, they ran on both the Micro-Labs and the Radio Shack graphics boards, and they came on disks with their own operating system, RAPIDOS. The Model 4 versions used the same disk format as TRSDOS 6 and LS-DOS, but the programs called RAPIDOS's own routines and would crash under any other DOS. RAPIDOS supported only single-sided disks, so the programs could not be moved to double-sided floppies or a hard drive. Shanafelt likened the disks to the old Model III self-booting games, "except that they are not copy protected."

He called Tournament Chess "easily the top Rapidos program, and one of the top TRS-80 games in general." Pieces are moved with the cursor keys or a joystick: you "hook" a piece with the space bar and release it on its new square. Every game also came with a low-resolution version with the same commands, for owners without a graphics board. Other RAPIDOS disks circulated as well. A 1987 Bits and Bytes article mentions a game on RAPIDOS, and in 1996 a Sydtrug member found GPRINT, a hi-res printing program "from RAPIDOS," on a disk he had been given.

In 1988 and 1989 owners of the MISOSYS XLR8er board, a Hitachi 64180 processor with extra memory, reported that the Rapidynamic games locked up. Some said that RAPIDOS would not boot at all with the XLR8er or the Alpha Technology memory boards. Ken Strickler raised it in The MISOSYS Quarterly (Winter 1988-89). A Tasmanian reader reported in Fall 1989 that RAPIDOS Chess was upsetting his grandchildren.

Roy Soltoff got a copy of Tournament Chess from Ted Carter of Micro-Labs and traced the fault. He reported it in "XLR8er/Graphics/Rapidos problem is the joystick software interface!" (The MISOSYS Quarterly, Spring/Summer 1989). The 64180 has 64 internal I/O registers. It treats an IN or OUT as internal when the high byte of the address bus is zero. In IN A,(n) that high byte is the contents of register A. Tournament Chess read the Alpha Products joystick port 00H with IN A,(0) in three places, each time with A equal to zero. So the 64180 read its own internal register 0 instead of the joystick, and got 12H instead of FFH. The game took 12H as UP, LEFT and RIGHT pressed at once. It ignored that impossible value, but because the joystick result was not empty it also skipped the keyboard scan, and the machine appeared to hang. There was no general conflict between RAPIDOS and the XLR8er, and no use of undocumented Z80 instructions: Carter said the author insisted none were used.

Soltoff offered three cures. One was a one byte change (XOR A for CPL) in each of the three routines, for owners without a joystick. Another was to change the port to 40H, since the Alpha Products stick decodes only A7, IN* and EXIOSEL* and answers on any port from 00H to 7FH. His own choice was a fuller patch that keeps register A non-zero for the port 0 reads, published as CHESSHX/FIX for the hi-res Tournament Chess 1.6.4. Carter then made XLR8er-safe versions of all the affected Rapidynamic programs by changing every IN A,(00H) to IN A,(40H). He offered updates to owners who sent their original disk and $1 for return postage. A reader sent patches for the backgammon game (GAMMONHX/FIX) in Spring 1990, and Soltoff worked up one for the low-resolution GAMMON.

Arthur N. McAninch found that the Alpha Technology board problem was different. Model 4 RAPIDOS 1.6 and 2.0 would not boot with it, but version 1.3 booted and ran normally. He moved all his hi-res programs onto 1.3 disks (The MISOSYS Quarterly, Spring/Summer 1989).

• 80 Micro, July 1985 (Gary A. Ludwick, "Rapidos: No Waiting"): five stars in every category. "Rapidos does work fast," but drive speed differences are "aggravating."
• NATGUG News, December 1985: Tournament Chess is "definitely recommended," and RAPIDOS "boots while you blink!"
• TRSTimes, Volume 2 Number 1, 1989: "I no longer dread the time to make copies."
• The MISOSYS Quarterly, Spring/Summer 1989 (Roy Soltoff): fast booting, but hardly a DOS.
• The MISOSYS Quarterly, Spring 1990 (a reader): "If it wasn't for the GAMES that run under it, I wouldn't have it!"
• Computer News 80, July 1992 (Gary W. Shanafelt): the Rapidynamic programs were of "generally high quality."